Device for combustion of solid fuel



Feb.. 1.5, 1944. s. G. pALEN DEVICE FOR COMBUSTIQN OF SOLID FUEL `Filed Nov. 2e, 1940 Patented Feb. 15, 1944 DEVICE Fon coMUs'rIoN or soLm FUEL Sten Gunnar Daln, Lidingo, Sweden, assignor to Svenska Aktiebolaget Gasaccumulator, Stockholm, Sweden, a corporation of Sweden l Application November 28, 1940, Serial No. 367,518

' combustion,

In Sweden November 21, 1939 2 Claims. (Cl. 110--30) My invention relates toga device for combustion of solid fuel.

Devices for continuous combustion of solid fuel are usually provided with regulating means for controlling the supply of air to the furnace according to the amount of heat required, These means inuence the air supply to the grate so that the combustion on the whole grate will be intensified when the need of heat is increased and reduced when need of heat is decreased. It is diiilcult, however, to vary the intensity of the combustion and thus also the heat output within wide limits with good'results. At heavy very high temperatures can be reached in the combustion zone, so that the furnace parts may be damaged. In case of very low heat output, on the other hand, `the temperature of the burning fuel zone will decrease so much that there will be a risk of stopping of the combustion.

It has therefore been suggestedto divide the grate in several Vsections and to admit combustion air to one or more of these sections according to the actual need of heat. The combustion is then regulated, entirely or partly, by increasing or decreasing the active grate area. Known devices of this kind, to which the present invention refers, operate with right-way combustion, i. e., the ash leaves the burning fuel layer in the opposite direction to the entering combustion air. As the variation of the active grate area in such a construction makes it necessary to divide the ash pit in the same number of sections as the grate, the removal of ash from the ash pit nvolves difficulties. vention these diiculties are avoided through reversed combustion, that is, the ash products escape from the burning fuel layer or at least from the parts of same situated next to the air inlet, substantially in the same direction as the combustion air is admitted to the fire, so that the ash is prevented from entering the air inlet ducts.

The invention will be described more in detail below with reference to the accompanying drawing, on which Fig. 1 shows a hot water boiler and Fig. 2 a cooking stove, to which the invention has been applicated.

In Fig. 1, reference character I indicates the fuel magazine of the boiler from which a solid fuel, for instance coke or anthracite, is fed between two substantially vertical grates 2 and 3. The combustion air is admitted through the grate 2 and the combustion gases escape through the grate 3 to the ues 4 and 5. The bars of the According to the present ingrate 2 are inclined so that the combustion air is directed obliquely downwards towards the fuel. The ash products formed fall down along the inside of the grate on an inclined plane 6, from there sliding down into an ash pan l. In this way ash is prevented from entering the inlet ducts for the combustion air. These ducts, indicated by 8, 9, I0 and II in the figure, are formed in the chamber in front of the grate 2, which by means of partitions is divided into four sections. Each of these sections is in communication with the atmosphere through an opening, regulated by means of a damper I2, I3, I4 or I5 respectively.

From the flue 4, which is separated from the flue 5 by a partition I 6, the combustion gases pass through tubes II of a lower hot water boiler I8. After passing the said tubes I'I the gases go upwards into a vertical flue I9, nally escaping through a'ue gas outlet 20. From the flue 5 the combustion gasespass through tubes 2I in an upper hotwater boiler 22 to the flue I9 and the outlet 20.

The lower. boiler I3 is preferably used for domestic hot water service, the upper boiler being intended to provide a, hot-water supply for radiator heating. By closing the two upper dampers I4 and I5 the combustion can be limited to the lower part of the furnace, situated in front of the air inlet ducts 8 and 5. In this way the combustion gases are admitted to the lower boiler I8 only. 'I'he combustion can also be limited to the lowest part of the furnace by combustion air being admitted through the duct 8 only. In this way the boiler may temporarily be used exclusively for the hot water production, for instance in summer time, and for hot water production as well as heating in the winter. In the latter case combustion air is also admitted to the ducts I0 and II, or one of them.

The grate 3 is provided with inclined bars in the same Way as the grate 2, so that the combustion products pass through the grate obliquely upwards. When falling down along the inside of the grate the ash is thus prevented from entering into the flues 4 and 5. The partition I6 between these flues does not impede the removal of ash. In case of vertical grates being used, as in the embodiment shown in Figure 1, the ash can be prevented from entering the air inlet ducts as well as the ilues. In such a case both these ducts can be divided in sections for regulating the supply of combustion air to different parts of the fuel layer and for drawing oli the claims.

combustion gases through diierent paths and! or to diierent heat consumption points.

In the cooking stove shown in Figure 2 the grate 30 is inclined and the fuel falls down upon same from a fuel magazine 3l. Above the layer of fuel, thus fed down to the grate, there is an inlet device 32 for supplying the combustion air. This device is provided with several separate air inlet openings, each of which independently may be shut o from the outer atmosphere so that combustion air can be admitted to one or more of these openings. The combustion air passes the fuel layer from above and downwards. The combustion products formed pass the grate in downward direction into the ash pit 34, and from there through the flue 35 to a cooking plate 3S and the flue outlet 31.

The invention is, of courseynot limited to the embodiments shown here but can be varied in several Ways within the scope indicated in the For instance, it is not necessary that the whole furnace is arranged for reversed combustion, but part of same, preferably the lowest part, can be arranged for rightway combustion. The removal of ash can then only take place through the air inlet duct leading to the part of the furnace which is arranged for right-way combustion, whereas ash is prevented from entering the air inlet ducts for the part or the parts of the furnace, where Areversed combustion is taking place.

Finally, the furnace maybe arranged for different specic heat output from the diierent parts oi same, in which case the specic 'heat output from the lowest part of the furnace preferably is lower than from the upper' parts. The

'lowest part of the furnace can, for instance, be

fia)

level, in which case these sections in their turn may be divided in vertical sections, which each one or in groups can be provided with separate air inlet ducts for variation of the supply of air to different parts of the furnace.

The invention can, of course, also be applicated to heating apparatus of other kinds than boilers and cooking stoves, and' is valuable in all instances Where the amount of heat required varies Widely.

What is claimed:

l. A solid fuel burning device including a pair of spaced substantially vertical grates, means for feeding solid fuel downwardly between said grates, means providing a plurality of separate channels for admitting combustion air through different yvertical portions of one of said grates, means for independently regulating flow of air through each of said channels, means providing separate passages for receiving products of combustion discharged through different vertical portions of the other of said grates, and a direrent heat absorbing element arranged in direct communication with separate passages whereby heat exchange relation is had with vthe gases passing through said separate passages.

v 2. A solid fuel burning device including a pair of spaced substantially vertical grates, means for feeding solid fuel downwardly between lsaid grates, means providing a plurality of separate channels for admitting combustion air through diierent vertical portions of one of said grates, 4means forindependently regulating now of air through each of said channels, means providing separate passages for receiving products of combustionA discharged through different vertical portions of the other of said grates, each of said passages receiving products of combustion from a region which is supplied with air through at least two of said channels, and a different heat absorbing element arranged in direct communication with separate passages whereby heat eX- change relation is had with gases passing through said separate passages.

l STEN GUNNAR DALN. 

